Fall 2023 Update on Kootenay Lake Water Levels and Conditions
On September 1, 2023, the International Joint Commission (IJC) Rule Curve for Kootenay Lake level switched to using the Queens Bay gauge at elevation 1745.32 feet for compliance measurements. The Rule Curve lowers prior to September 1 to allow farmers in the Kootenai Flats region to work their fields without an elevated water table. This maximum level will continue until January 7, 2024, when the Rule Curve will begin slowly decreasing to 1739.32 feet to allow for freshet water storage (Figure 1).
Figure 1: Kootenay Lake maximum lake elevations as defined by the IJC 1938 Order of Approval rule curve.
Although the basin experienced persistently dry conditions through the summer with below-average inflows to Kootenay Lake, the current lake level as measured at the Queens Bay hydrometric gauge remains near the historical mean and is below the Order of Approval Rule Curve for this time of year. Kootenay Lake levels are expected to remain the same or slightly higher for the duration of autumn and into winter as precipitation increases. Since mid-August, outflows from Kootenay Lake are predominantly controlled by Grohman Narrows and not Corra Linn Dam.
Figure 2: Kootenay Lake levels at Queens Bay (green) and Nelson (orange), lake outflow control by Corra Linn (pink) or Grohman Narrows (purple), and the International Joint Commission 1938 Order of Approval Rule Curve for 2022 (red). Credit: FortisBC (data) and Environment and Climate Change Canada (plot), 2023.
Warmer-than-average temperatures continued into July and August, followed by a relatively normal temperature range in September and a warm start to October (Figure 3). These warm temperatures have contributed to persisting drought conditions in the basin.
Figure 3: Nelson, British Columbia, daily mean temperatures for the past three months (black), long-term mean (dashed grey), standard deviations above and below the mean (red and blue, respectively).
Snow accumulation in the basin is off to a below-normal start this year, with minimal snow cover as seen in the Redfish Creek Snow Station Satellite Camera image, taken November 6 (Figure 4).
Figure 4: Redfish Creek (2D14P) snow pillow station in the Kootenay River basin. Credit: BC Ministry of Environment and Climate Strategy
- Winter 2023-2024 is expected to be an El Niño year, which typically brings warmer temperatures to the region. Effects on precipitation are undetermined.
- Portal.Drought levels are currently at Level 4 (adverse impacts likely) for the East Kootenay basin and Level 3 (adverse impacts possible) for the West Kootenay basin. Up-to-date drought information can be found through the British Columbia Drought Information
- The International Kootenay Lake Board of Control held its board and public meetings on September 19, 2023. The public meeting was well-attended, with more than 30 people joining in person and online. A recording of the public meeting is featured on the board website at ijc.org/en/klbc.
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Sonja Michelsen, US Secretary
Martin Suchy, Canadian Secretary